Dynamic Earth 1 1 0 Dynamic Earth Learning

Dynamic Earth 1

1. 0 Dynamic Earth Learning Intentions You will be able to: § Name and describe the layers of the earth. § Explain what crustal plates are, and why they move. § Describe what happens when plates separate, collide or slide past each other. 1

1. 1 Our Moving Continents Dynamic Earth Over 250 million years ago, the earth’s continents were connected as one large landmass, known as Pangaea. Over time, the continents broke apart and moved. This process is known as continental drift. 250 million Present 200 145 65 million day yearsago 1

1. 2 Structure of the Earth The structure of the earth Dynamic Earth 1 Plate: A large slab of the earth’s crust Plate boundary: Where plates meet. Crust: The thin outer layer of the earth. Mantle: Consists of hot molten and semimolten rock known as magma. It moves around in very slow currents. Outer core: Consists of liquid nickel and iron – this is molten. Inner core: The solid centre of the earth. Temperates are up to 6, 000° Celsius.

1. 3 Convection Currents Dynamic Earth 1 The earth’s core heats the magma, causing it to rise towards the crust As the magma rises, it then begins to cool The magma becomes heavier and sinks down towards the core This continuous cycle causes a circular movement of magma (convection currents) in the mantle Convection currents cause plates to move very slowly

1. 3 Convection Currents Dynamic Earth 1 Convection currents cause tectonic plates to move very slowly. The plates can be: Dragged apart (separating plates) Pushed together (colliding plates) Slide past each other (sliding plates) Separating plates Colliding plates Sliding plates

1. 4 Plate Tectonics Dynamic Earth Plate tectonics means that the earth is made up of large, moving plates of solid rock. Earth’s principal plates 1

Dynamic Earth Video: Seeing Plate Tectonics 1